In general, a foam generator mixes liquid contents stored in a receptacle with air in an air and liquid mixing chamber and then forms and discharges uniform foam liquid through a filtration net. Such a foam generator is used for various purposes, such as shampoos, hair cosmetics, or cleansers used in bathrooms, kitchens, and restrooms.
A conventional foam generator is used to mix liquid contents with an appropriate amount of air and to extrude the mixture in the form of foam. In products to which such a foam generator is applied, a receptacle must be filled with compressed gas, making it technically difficult to manufacture the receptacle. The receptacle must be shaken whenever the receptacle is used. Also, in the state in which the product receptacle is inclined, the liquid filling the receptacle cannot be ejected in the form of foam, and only the compressed gas is ejected.
In order to solve the above problem, a foaming pump assembly that appropriately mixes liquid contents with external air and ejects the mixture in the form of foam without filling the foaming pump assembly with compressed air or without shaking the foaming pump assembly is disclosed in Korean Registered Utility Model No. 20-0169773 (Title of the Device: Air valve device of foam generator).
As shown in FIG. 1, the foaming pump assembly disclosed in Korean Registered Utility Model No. 20-0169773 includes a cap 1 coupled to the neck of a receptacle A having (liquid) contents stored therein in a screw coupling manner, a cylinder body 2 fixed in the cap 1, the cylinder body 2 having an air cylinder 2a having a negative pressure hole 2b formed therein and a long cylindrical liquid cylinder 2c integrally formed at the center of the lower part of the air cylinder 2a such that the (liquid) contents are introduced into the liquid cylinder 2c, a nozzle 3 installed to the cap 1 so as to be supported by the cap 1 such that one end thereof can be movable into the cylinder body 2, the nozzle 3 having an outlet 3a, through which foam is ejected, an air piston 4 having an upper part fixed to the inner circumference of the nozzle 3 and the outer circumference of a lower end disposed in tight contact with the inner circumference of the air cylinder 2a such that the air piston 4 presses the lower part of the air cylinder 2a and expands the upper part of the air cylinder 2a when the nozzle 3 is pushed, a liquid piston 6 disposed between a coil spring 5 provided at the lower part of the liquid cylinder 2c of the cylinder body 2 and the air piston 4 for elastically supporting the nozzle 3 upward and guiding the compressed air and the contents to the upper part of the air piston 4, and a ball 8 located at the bottom part of the liquid cylinder 2c of the cylinder body 2 for selectively opening and closing a liquid suction port 7. A filtration net 9 for filtering foam is disposed in the nozzle 3.
In the conventional foaming pump assembly, when the nozzle 3 is repeatedly pushed, the (liquid) contents filling the receptacle A are suctioned/pumped through the liquid cylinder 2c. At the same time, air is ejected from the air cylinder 2a. As a result, foam is generated. The foam is uniformly filtered through the filtration net 9 and is then ejected to the outside through the outlet 3a in the nozzle 3. In the conventional foaming pump assembly, however, the coil spring 5 and the ball (steel ball) 8, which are made of metal, are disposed in the liquid cylinder 2c, which is a suction channel of the liquid contents. In the case in which the foaming pump assembly is used for a long period of time, therefore, the coil spring 5 and the ball 8 may be corroded by the liquid contents. Furthermore, the quality of the liquid contents may be changed.
Particularly, in recent years, the foaming pump assembly has come to be applied to products containing various functional contents. Since the metal coil spring 5 and the metal ball 8 remains in contact with the contents in the liquid cylinder 2c, the coil spring 5 and the ball 8 may be corroded.